In insertion order, which is topological.
Indices into nodes; a product's graph has one.
"MAJOR.MINOR": the lowest version the content needs, "1.0" unless
a station carries a seam-snapping window (#423), then "1.1", or a
run's sections do (#429), then "1.2", or an offset run continues to
a basis end the kernel measures (#433), then "1.3", or a polygonal
bounded half-space clips (#515), then "1.4" (axiolid/kernel#297,
#301, #303, #321).
This build writes at most "1.4".
Axiolid's versioned wire format of a geometry graph, 1.0 to 1.4 (Axiolid ADR 0085). A reader refuses another
format, a majorversionother than its own, a newer minor, and any kind, variant or field it does not know.